posted on Jul, 16 2014 @ 07:12 PM
This is very likely a collapsed geologic feature called a Pingo
A pingo is a massive underground column of water that freezes and expands into a massive ice columns (some are over half a kilometer wide and can
reach 70m above the ground). These columns push the ground up and out. Eventually the ice melts (as would be especially likely in the recent warm
weather) and the support collapses leaving the upturned earth and potentially a cavern below. You can see a collapsed pingo
on this page
(scroll down for the "collapsed pingo" image).
Here is another.
Now, the void in this particular incident is unusual, but not entirely unexpected. Researchers have found the permafrost in the region can exceed
thickness of 300m which would easily account for such a cavern if there was a melt and then collapse in support structure (Permafrost: Second
International Conference, July 13-28, 1973).
In fact, there are records of similar events from ice collapses occuring in 1989-1990 (Encyclopedia of the Arctic
By Mark Nuttall).
"During the last 100 years, whole islands composed of ice rich deposits have disappeared. In 1989-1990, catastrophic activation of fround ice slumps
took place on Tamyr and Yamal peninsulas.
The large structers are called "thermal denudation" or "kettles" elsewhere. And the smaller structures are "thaw slumps."
Pretty extraordinary to see a fresh one, but we can say pretty confidentally what it was caused by.